Processing of oil by steam addition

ABSTRACT

Salt is removed from crude oil by exposing the salt bearing crude to successive stages of water injection and steam injection where the water injection includes high shear and the stream injection does not include high shear applied to the steam bubbles. The steam is seen to transfer salt from the crude via a different transfer mechanism and therefore doesn&#39;t require the high shear mixing of conventional water injection systems.

CROSS-REFERENCE TO RELATED APPLICATIONS

None.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

None.

FIELD OF THE INVENTION

This invention relates to improving the efficiency of refining crude oiland especially to removing salt from crude oil in a refinery.

BACKGROUND OF THE INVENTION

Refineries typically obtain crude oil from a number of sources havingdifferent characteristics such as viscosity, density, sulfur content,salt and other impurities, etc. Each of these crudes are delivered to arefinery via pipelines, ships and other crude carriers and stored inlarge tanks until the refinery is ready to refine it. Typically, arefinery works to blend various crudes in preferred proportionsrecognizing that each of the various crudes have different levels oftheir constituent components, both good and bad, in an attempt tooptimize the utility of the various systems with that specific refinery.One of the first operations in the refinery for processing the crude oilis to remove salt and other contaminants from the crude. Salts that aretypically found in crude oil are chlorides of sodium, magnesium andcalcium and it is necessary to remove these salts to avoid the creationof hydrochloric acid within the refinery which is highly corrosive. Saltis typically removed by injecting clean water into the crude oil suchthat water droplets are dispersed into the crude oil such that any saltin the crude may be captured or transferred into the water. To absorbthe greatest amount of salt, it is generally desired to create a greatnumber of reasonably small water droplets in the crude oil to transferthe salt into those droplets. However, the refinery operator wants aslittle water taken up into the refinery from the desalter system aspossible. So while it is desirable to have a lot of very small droplets,it is also desirable that a minimal amount of water is put into thecrude oil and that the water droplets are amenable to being quickly andeasily removed from the crude oil after the salt has been captured bythe water droplets.

As the water must be removed, the droplets are typically removed basedon density differences between the crude oil and the water by allowingthe emulsion to rest in a large settling vessel where the heavier watersettles to the bottom. Unfortunately, this can be a slow process,especially when the droplets are very small and tend to settle veryslowly. This problem is particularly challenging for more viscous anddenser crude oils. One approach to aid removal of the water droplets isto reduce the viscosity of the crude by heating. So, it is not uncommonfor refineries to heat the crude oil as it comes into the desaltersystem to reduce the effective viscosity of the crude oil and acceleratethe rate that droplets descend to the bottom of the settling tank.

Another approach has been to increase the coalescence of water dropletsby imposing an electric field that cause the water droplets to beconcentrated together and form larger droplets that separate faster.Other coalescer technologies where the emulsion is gently mixed to againbring the water droplets together to coalesce have been proposed.

Clearly, refineries work best when the crudes have less undesirablematerials dissolved therein and any opportunity to efficiently andsimply remove such contaminants from the crude oil would be wellreceived by refinery operators.

BRIEF SUMMARY OF THE DISCLOSURE

The invention more particularly relates to a process for reducingelectrical energy consumption for pumping crude oil from at least oneremote storage tank through a pipe to a desalter system in a refinery.The process includes the creation of steam, identifying crude oil thatis about to be pumped through a pipe from a remote storage tank to thedesalter system in the refinery and identifying a location in the pipeat which steam may be added to the crude oil as it is to pass throughalong the way from the storage tank to the desalter system. Crude oil isthen pumped through the pipe to the desalter system and steam isinjected into the crude oil in the pipe such that the crude oil isheated by the steam thereby lowering viscosity of the crude oil andreducing resistance to flow and thereby reducing the electric energyrequirement to move the crude oil to the desalter system where thecondensed steam is removed from the crude oil in the desalter system.

The invention more particularly relates to a process for removing saltfrom crude oil wherein the salt may be in the form of particles ofcrystalline salt suspended in the crude oil or as small droplets ofbrine water suspended in the crude oil, or both. The process comprisesinjecting steam into the crude oil in the form of steam bubbles that arequite large relative to any salt particles or relative to any smalldroplets of brine water so as to create steam bubbles that will havesubstantial contact with the crude oil along with any nearby suspendedsalt particles and brine droplets, such that a single steam bubble maycontact numerous salt particles and brine droplets. The steam iscondensed into droplets of liquid water while at the same time the steamdissolves available salt particles resulting in new brine droplets andalso delivers a portion of the water, whether liquid or vapor, withinsteam bubbles into any available small brine droplets enlarging thebrine droplets to a size more amenable for separation from the crudeoil. The liquid water is then separated from the crude oil where theliquid water has the salt dissolved therein. The process is particularlycharacterized in that it does not include imposing high shear mixing ofthe injected steam to increase contact between the suspended salt andeither the steam or the resulting water.

The invention more particularly relates to a process for removing saltfrom crude oil wherein the salt may be in the form of particles ofcrystalline salt suspended in the crude oil or as small droplets ofbrine water suspended in the crude oil, or both. The process includesinjecting steam into the crude oil in the form of steam bubbles that arequite large relative to any salt particles or relative to any smalldroplets of brine water so as to create steam bubbles that will havesubstantial contact with the crude oil along with any nearby suspendedsalt particles and brine droplets, such that a single steam bubble maycontact numerous salt particles and brine droplets. The steam bubblescollapse and condense into droplets of liquid water while at the sametime dissolves available salt particles or crystals creating new brinedroplets and also delivering a portion of the water, whether vaporous orliquid, within steam bubbles into any available small brine dropletsresulting in enlarged brine droplets having a size more amenable forseparation from the crude oil. Liquid water is also injected into thecrude oil before during or after the steam is injected and aggressivehigh shear mixing is imposed on the crude oil with water therein in ahigh shear mixer to enhance contact between salt particles, brinedroplets and water droplets to enhance dissolving of salt particles andcoalescence of brine droplets with water. The liquid water is thenseparated from the crude oil where the separated water includes the saltdissolved therein. The process is characterized in that it does notinclude imposing high shear mixing of uncondensed steam bubbles withinthe crude oil to increase contact between injected water and thesuspended salt.

The invention more particularly relates to a process for removing saltfrom crude oil wherein the salt may be in the form of particles ofcrystalline salt suspended in the crude oil or as small droplets ofbrine water suspended in the crude oil, or both. The process includesinjecting liquid water into the crude oil and imposing aggressive highshear mixing on the crude oil and water in a high shear mixer to breakup the injected water into smaller droplets of water and, at the sametime, enhance contact of the smaller droplets of water with saltparticles and brine droplets to enhance dissolving of salt particles andalso coalesce droplets of water whether brine droplets or droplets ofinjected water. After the aggressive high shear mixing, the processincludes injecting steam into the crude oil in the form of steam bubblesthat are quite large relative to any salt particles or relative to anybrine droplets and also relative to water droplets so as to create steambubbles that will have substantial contact with the crude oil along withany nearby suspended salt particles and other droplets, such that asingle steam bubble may actually contact numerous salt particles andwater droplets. The steam bubbles are then condensed into droplets ofliquid water while at the same time dissolving available salt particlesforming new brine droplets and also delivering a portion of the water,whether liquid or vapor, within steam bubbles into any available waterand brine droplets resulting in enlarged water and brine droplets havinga size more amenable for separation from the crude oil. Thereafter, theliquid water is separated from the crude oil such that the saltdissolved goes with the separated water. This process is particularlycharacterized in that it does not include imposing high shear mixing ofuncondensed steam bubbles within the crude oil.

The invention more particularly relates to a process for removing saltfrom crude oil wherein the salt may be in the form of particles ofcrystalline salt suspended in the crude oil or as small droplets ofbrine water suspended in the crude oil, or both. The process includesinjecting steam into the crude oil in the form of steam bubbles that arequite large relative to any salt particles or relative to the any smalldroplets of brine water so as to create steam bubbles that will havesubstantial contact with the crude oil along with any nearby suspendedsalt particles and with brine droplets, such that a single steam bubblemay actually contact many salt particles and brine droplets. The steambubbles collapse and condense into droplets of liquid water while at thesame time dissolving available salt particles forming new brine dropletsand also delivering a portion of the water, whether liquid or vapor,within steam bubbles into any available small brine droplets resultingin enlarged brine droplets having a size more amenable for separationfrom the crude oil. The liquid water is then separated from the crudeoil such that the water has the salt dissolved therein to thereby removethe salt and water from the crude oil and thereby form a first passdesalted crude oil. This process is particularly characterized in thatit does not impose high shear mixing on steam bubbles or resultingcondensed water prior to water separation from the crude oil.Thereafter, liquid water is injected into the first pass desalted crudeoil and aggressive high shear mixing is imposed on the injected waterand first pass desalted crude oil to break up the injected water intosmaller droplets of water and, at the same time, enhance contact of thesmaller droplets of water with remaining salt particles and remainingbrine droplets to enhance dissolving of salt particles and also tocoalesce droplets of water whether brine droplets or droplets ofinjected water. Thereafter, the liquid water is separated from the firstpass desalted crude oil with any salt dissolved in the water to therebyremove salt and water from the first pass desalted crude.

The invention more particularly relates to a process for removing saltfrom crude oil wherein the salt may be in the form of particles ofcrystalline salt suspended in the crude oil or as small droplets ofbrine water suspended in the crude oil, or both. The process includesinjecting a first stream of steam into the crude oil in the form ofsteam bubbles that are quite large relative to any salt particles orrelative to any small droplets of brine water so as to create steambubbles that will have substantial contact with the crude oil along withany nearby suspended salt particles and brine droplets, such that asingle steam bubble may actually contact numerous salt particles andbrine droplets. Water is injected before, after or concurrently with thesteam and the steam bubbles collapse and condense into droplets ofliquid water while at the same time dissolving available salt particlesforming new brine droplets and also delivering a portion of the liquidor vaporous water within steam bubbles into any available small brinedroplets resulting in enlarged brine droplets having a size moreamenable for separation from the crude oil. After the steam bubbles havecollapsed and condensed and the water is injected, aggressive high shearmixing is imposed on the crude oil and water in a high shear mixer toenhance contact between salt particles, brine droplets and waterdroplets to enhance dissolving of salt particles and coalescence ofbrine droplets with water. Then the liquid water is separated from thecrude oil where the salt is dissolved in the water and goes out with thewater and the crude oil from the separator forms a first pass desaltedcrude oil. Thereafter, a second stream of steam is injected into thefirst pass desalted crude oil in the form of steam bubbles that arequite large relative to any remaining salt particles or relative to theany remaining droplets of brine water so as to create steam bubbles thatwill have substantial contact with the first pass desalted crude oilalong with any nearby suspended salt particles and brine droplets. Thisway, a single steam bubble may actually contact numerous remaining saltparticles and remaining brine droplets. Thereafter, the steam bubblescollapse and condense in the first pass desalted crude oil into dropletsof liquid water while at the same time dissolving any remainingavailable salt particles creating new brine droplets and also deliveringa portion of the water, whether liquid or vapor, within steam bubblesinto any remaining available small brine droplets resulting in enlargedbrine droplets having a size more amenable for separation from the firstpass desalted crude oil. The liquid water is then separated from thefirst pass desalted crude oil where salt is dissolved in the water andthe crude from this second separation is a twice desalted crude oil. Theprocess is particularly characterized in that it does not includeimposing high shear mixing of uncondensed steam bubbles within the crudeoil or within the first pass desalted crude oil.

The invention more particularly relates to a process for removing saltfrom crude oil wherein the salt may be in the form of particles ofcrystalline salt suspended in the crude oil or as small droplets ofbrine water suspended in the crude oil, or both. The process includesinjecting liquid water into the crude oil and then imposing aggressivehigh shear mixing on the crude oil and water in a high shear mixer tobreak up the injected water into smaller droplets of water and, at thesame time, create impactful contacts of the smaller droplets of waterwith salt particles and brine droplets to enhance dissolving of saltparticles and also coalesce droplets of water whether brine droplets ordroplets of injected water. After the aggressive high shear mixing,steam is injected into the crude oil in the form of steam bubbles thatare quite large relative to any salt particles or relative to any brinedroplets and also relative to water droplets so as to create steambubbles that will have substantial contact with the crude oil along withany nearby suspended salt particles and other droplets, such that asingle steam bubble may actually contact a number of salt particles andwater droplets. The steam bubbles are condensed into droplets of liquidwater while at the same time dissolving available salt particles tocreate new brine droplets and also delivering a portion of the water,whether liquid or vapor, within steam bubbles into any available waterand brine droplets resulting in enlarged water and brine droplets havingsizes more amenable for separation from the crude oil. The liquid wateris then separated from the crude oil where the liquid water separatedfrom the crude includes salt dissolved therein that had been suspendedin the crude oil such that the crude oil is then deemed a first passdesalted crude oil. The first pass desalted crude then has a secondinjection of a steam in the form of steam bubbles that are quite largerelative to any remaining salt particles or relative to any remainingbrine droplets so as to create steam bubbles that will have substantialcontact with the first pass desalted crude oil along with any nearbysuspended salt particles and other droplets, such that a single steambubble may contact a number of salt particles and water droplets. Thesteam bubbles are then collapsed and condensed into droplets of liquidwater while at the same time dissolving available salt particlescreating new brine droplets and also delivering a portion of the water,whether liquid or vapor, within steam bubbles into any available waterdroplets and any remaining available brine droplets resulting inenlarged water and brine droplets having a size more amenable forseparation from the first pass desalted crude oil. Then, the liquidwater in the first pass desalted crude oil is separated such that saltdissolved in the liquid water goes with the water leaving a second passdesalted crude oil. The process is particularly characterized in that itdoes not include imposing high shear mixing of uncondensed steam bubbleswithin the crude oil.

The invention more particularly relates to a process for heating crudeoil and also removing salt from crude oil wherein the salt may be in theform of particles of crystalline salt suspended in the crude oil or assmall droplets of brine water suspended in the crude oil, or both. Theprocess includes creating steam and moving crude oil having suspendedsalt therein through a vessel having walls on all sides except for aninlet and an outlet. Steam is injected steam into the moving crude oilat a location within the crude oil in such a manner that as the injectedsteam enters the crude oil, it forms steam bubbles about which at least95% of the steam bubbles condense and collapse into water dropletswithin the crude oil without ever contacting any walls of the vessel. Asthe steam bubbles condense and collapse, salt that was suspended in thecrude oil is transferred to water resulting from condensed steam bubblesby contacting the salt with water before during or after steam bubblecondensation. The water is then separated and removed from the crude oilwhere the water takes salt that had been suspended in the crude oil withit.

The invention more particularly relates to a process for removing saltfrom crude oil wherein the salt may be in the form of particles ofcrystalline salt suspended in the crude oil or as small droplets ofbrine water suspended in the crude oil, or both. The process includesinjecting steam into the crude oil in the form of steam bubbles that arequite large relative to any salt particles or relative to the any smalldroplets of brine water so as to create steam bubbles that will havesubstantial contact with the crude oil along with any nearby suspendedsalt particles and brine droplets, such that a single steam bubble mayactually contact many salt particles and brine droplets. Before, duringor after the steam is injected, a first stream of liquid water is alsoinjected into the crude oil. The steam bubbles are condensed intodroplets of liquid water while at the same time dissolving availablesalt particles creating new brine droplets and also delivering a portionof the water, whether liquid or vapor, within steam bubbles into anyavailable small brine droplets resulting in enlarged brine dropletshaving a size more amenable for separation from the crude oil. After thesteam bubbles have collapsed and condensed, aggressive high shear mixingis imposed on the crude oil and water in a high shear mixer to enhancecontact between salt particles, brine droplets and water droplets toenhance dissolving of salt particles and coalescence of brine dropletswith water. The liquid water is then separated from the crude oil wherethe water takes the dissolved salt dissolved with it and the remainingcrude oil is deemed a first pass desalted crude oil. Then, the firstpass desalted crude oil gets a second injection of liquid water followedaggressive high shear mixing in a high shear mixer to enhance contactbetween salt particles, brine droplets and water droplets to enhancedissolving of salt particles and coalescence of brine droplets withwater. The liquid water is then separated from the first pass desaltedcrude oil where the separated water includes salt dissolved therein thathad just previously been suspended in the crude oil so that the crudeoil after the water is separated is deemed to be a twice desalted crudeoil. The process is particularly characterized in that it does notinclude imposing high shear mixing of uncondensed steam bubbles withinthe crude oil.

The invention more particularly relates to a process for removing saltfrom crude oil wherein the salt may be in the form of particles ofcrystalline salt suspended in the crude oil or as small droplets ofbrine water suspended in the crude oil, or both. The process includesinjecting a first stream of liquid water into the crude oil and imposingaggressive high shear mixing on the crude oil and water in a high shearmixer to enhance contact between salt particles, brine droplets andwater droplets to enhance dissolving of salt particles and coalescenceof brine droplets with water. Thereafter, steam is injected into thecrude oil in the form of steam bubbles that are quite large relative toany salt particles or relative to the any droplets of water includingbrine water so as to create steam bubbles that will have substantialcontact with the crude oil along with any nearby suspended saltparticles and brine droplets, such that a single steam bubble mayactually contact many salt particles and water droplets. The steambubbles are condensed and collapsed into droplets of liquid water whileat the same time dissolving available salt particles creating new brinedroplets and also delivering a portion of the water, whether liquid orvapor, within steam bubbles into any available water droplets resultingin enlarged water droplets having a size more amenable for separationfrom the crude oil. The liquid water is then separated from the crudeoil where the separated water includes salt dissolved therein and thecrude oil from this separation forms a first pass desalted crude oil. Asecond stream of liquid water is injected into the first pass desaltedcrude oil and aggressive high shear mixing is imposed on the first passdesalted crude oil and water in a high shear mixer to enhance contactbetween salt particles, brine droplets and water droplets to enhancedissolving of salt particles and coalescence of brine droplets withwater. Liquid water is then separated and removed from the first passdesalted crude oil where the water includes dissolved salt that waspreviously suspended in the first pass desalted crude oil. With thissecond stage water removal, the crude oil is deemed a twice desaltedcrude oil. The overall process is particularly characterized in that itdoes not include imposing high shear mixing of uncondensed steam bubbleswithin the crude oil.

The invention more particularly relates to a process for removing saltfrom crude oil wherein the salt may be in the form of particles ofcrystalline salt suspended in the crude oil or as small droplets ofbrine water suspended in the crude oil, or both. The process includesinjecting a first stream of steam into the crude oil in the form ofsteam bubbles that are quite large relative to any salt particles orrelative to the any small droplets of brine water so as to create steambubbles that will have substantial contact with the crude oil along withany nearby suspended salt particles and brine droplets, such that asingle steam bubble may actually contact numerous salt particles andbrine droplets. The steam bubbles are condensed into droplets of liquidwater while at the same time dissolving available salt particles formingnew brine droplets and also delivering a portion of the water, whetherliquid or vapor, within steam bubbles into any available small brinedroplets resulting in enlarged brine droplets having a size moreamenable for separation from the crude oil. The liquid water is thenseparated and removed from the crude oil where the removed waterincludes dissolved salt therein that was suspended in the crude oilwhere the separated crude oil thereby forms a first pass desalted crudeoil. Liquid water is then injected into the first pass desalted crudeoil and aggressive high shear mixing is imposed on the injected waterand first pass desalted crude oil to break up the injected water intosmaller droplets of water and, at the same time, create impactfulcontacts of the smaller droplets of water with remaining salt particlesand remaining brine droplets to enhance dissolving of salt particles andalso to coalesce the droplets of water whether brine droplets ordroplets of injected water. After the aggressive high shear mixing, asecond stream of steam is injected into the first pass desalted crudeoil in the form of steam bubbles that are quite large relative to anysalt particles or relative to the any small droplets of brine water soas to create steam bubbles that will have substantial contact with thefirst pass desalted crude oil along with any nearby remaining suspendedsalt particles and remaining water droplets including any remainingbrine droplets, such that a single steam bubble may actually contactnumerous salt particles and brine droplets. The steam bubbles arecondensed into droplets of liquid water while at the same time the steambubbles dissolve any remaining and available salt particles resulting innew brine droplets and also delivering a portion of the water, either orboth liquid and vapor, within steam bubbles into any remaining andavailable small brine droplets resulting in enlarged brine dropletshaving a size more amenable for separation from the crude oil. Theliquid water is then separated and removed from the first pass desaltedcrude oil where any dissolved salt is in the removed water and the crudeoil is then twice desalted. The overall process is particularlycharacterized in that it does not include imposing high shear mixing ofuncondensed steam bubbles within the crude oil.

The invention more particularly relates to a process for removing saltfrom crude oil wherein the salt may be in the form of particles ofcrystalline salt suspended in the crude oil or as small droplets ofbrine water suspended in the crude oil, or both. The process includesinjecting a first stream of steam into the crude oil in the form ofsteam bubbles that are quite large relative to any salt particles orrelative to the any small droplets of brine water so as to create steambubbles that will have substantial contact with the crude oil along withany nearby suspended salt particles and brine droplets, such that asingle steam bubble may actually contact numerous salt particles andbrine droplets. The steam bubbles are condensed into droplets of liquidwater while at the same time dissolving available salt particlescreating new brine droplets and also delivering a portion of the water,either or both liquid and vapor, within steam bubbles into any availablesmall brine droplets resulting in enlarged brine droplets having a sizemore amenable for separation from the crude oil. The liquid waterresulting from the condensation of the steam bubbles is then separatedand removed from the crude oil including water with dissolved salttherein to thereby remove the salt and water from the crude oil andthereby form a first pass desalted crude oil. The first pass desaltedcrude oil then receives a second stream of steam injected in the form ofsteam bubbles that are quite large relative to any salt particles orrelative to the any small droplets of brine water so as to create steambubbles that will have substantial contact with the first pass desaltedcrude oil along with any nearby remaining suspended salt particles andremaining water droplets including any remaining brine droplets, suchthat a single steam bubble may actually contact numerous salt particlesand brine droplets. The steam bubbles are collapsed and condensed intodroplets of liquid water while at the same time dissolving any remainingand available salt particles forming new brine droplets and alsodelivering a portion of the water, either liquid or vapor or both,within steam bubbles into any remaining and available small brinedroplets resulting in enlarged brine droplets having a size moreamenable for separation from the crude oil. Thereafter, liquid water isinjected into the first pass desalted crude oil which is then subjectedto aggressive high shear mixing to break up the injected water intosmaller droplets of water and, at the same time, create impactfulcontacts of the smaller droplets of water with remaining salt particlesand remaining brine droplets to enhance dissolving of salt particles andalso coalesce droplets of water whether brine droplets or droplets ofinjected water. The liquid water is then separated and removed from thefirst pass desalted crude oil with any dissolved salt therein to therebyremove salt and water from the first pass desalted crude. The overallprocess is particularly characterized in that it does not includeimposing high shear mixing of uncondensed steam bubbles within the crudeoil.

The invention more particularly relates to a process for removing saltfrom crude oil wherein the salt may be in the form of particles ofcrystalline salt suspended in the crude oil or as small droplets ofbrine water suspended in the crude oil, or both. The process includesinjecting a first stream of steam into the crude oil in the form ofsteam bubbles that are quite large relative to any salt particles orrelative to the any small droplets of brine water so as to create steambubbles that will have substantial contact with the crude oil along withany nearby suspended salt particles and brine droplets, such that asingle steam bubble may contact numerous salt particles and brinedroplets. The steam bubbles are collapsed and condensed into droplets ofliquid water while at the same time dissolving available salt particlesforming new brine droplets and also delivering a portion of the water,as either liquid or vapor or both, within steam bubbles into anyavailable small brine droplets resulting in enlarged brine dropletshaving a size more amenable for separation from the crude oil. Eitherbefore, after or concurrently with the steam injection, a first streamof liquid water is injected into the crude oil. After the steam bubbleshave all collapsed and condensed, aggressive high shear mixing isimposed on the injected water and the crude oil to break up the injectedwater into smaller droplets of water and, at the same time, enhancecontact of the smaller droplets of water with remaining salt particlesand remaining brine droplets to enhance dissolving of salt particles andalso coalesce droplets of water whether brine droplets or droplets ofinjected water. The liquid water in the crude oil is then separated andremoved from the crude oil where the water includes dissolved salttherein to thereby remove the salt and water from the crude oil andalso, thereby, form a first pass desalted crude oil. Into the first passdesalted crude oil, a second stream of steam is injected in the form ofsteam bubbles that are quite large relative to any salt particles orrelative to the any small droplets of brine water so as to create steambubbles that will have substantial contact with the first pass desaltedcrude oil along with any nearby remaining suspended salt particles andremaining water droplets including any remaining brine droplets, suchthat a single steam bubble may contact numerous salt particles and brinedroplets. The steam bubbles are then collapsed and condensed intodroplets of liquid water while at the same time dissolving any remainingand available salt particles forming new brine droplets and alsodelivering a portion of the water, as either liquid or vapor or both,within steam bubbles into any remaining and available small brinedroplets resulting in enlarged brine droplets having a size moreamenable for separation from the crude oil. A second stream liquid wateris injected into the first pass desalted crude oil and after the steambubbles have fully collapsed and condensed, a second round of aggressivehigh shear mixing is imposed on the injected water and first passdesalted crude oil to break up the injected water into smaller dropletsof water and, at the same time, enhance contact of the smaller dropletsof water with remaining salt particles and remaining brine droplets toenhance dissolving of salt particles and also coalesce droplets of waterwhether brine droplets or droplets of injected water. Thereafter, theliquid water is separated and removed from the first pass desalted crudeoil along with any dissolved salt therein to thereby remove salt andwater from the first pass desalted crude. The overall process isparticularly characterized in that it does not include imposing highshear mixing of uncondensed steam bubbles within the crude oil.

The invention more particularly relates to a process for removing saltfrom crude oil wherein the salt may be in the form of particles ofcrystalline salt suspended in the crude oil or as small droplets ofbrine water suspended in the crude oil, or both. The process includesinjecting a first stream of liquid water into the crude oil and thenimposing aggressive high shear mixing on the injected water and thecrude oil to shred the injected water into smaller droplets of waterand, at the same time, enhance contact of the smaller droplets of waterwith remaining salt particles and remaining brine droplets to enhancedissolving of salt particles and also coalesce droplets of water whetherbrine droplets or droplets of injected water. After the aggressive highshear mixing, a first stream of steam is injected into the crude oil inthe form of steam bubbles that are quite large relative to any saltparticles or relative to the any small droplets of brine water so as tocreate steam bubbles that will have substantial contact with the crudeoil along with any nearby suspended salt particles and brine droplets,such that a single steam bubble may contact numerous salt particles andbrine droplets. The steam bubbles collapse and condense into droplets ofliquid water while at the same time dissolve available salt particlesforming new brine droplets and also delivering a portion of the water,as liquid or vapor or both, within steam bubbles into any availablesmall brine droplets resulting in enlarged brine droplets having a sizemore amenable for separation from the crude oil. Liquid water is thenseparated from the crude oil where water includes dissolved salt thereinto thereby remove the salt and water from the crude oil and thereby forma first pass desalted crude oil. A second stream of liquid water isinjected into the first pass desalted crude oil and aggressive highshear mixing is imposed on the injected water and first pass desaltedcrude oil to break up the injected water into smaller droplets of waterand, at the same time, enhance contact of the smaller droplets of waterwith remaining salt particles and remaining brine droplets to enhancedissolving of salt particles and also coalesce droplets of water whetherbrine droplets or droplets of injected water. After the aggressive highshear mixing, a second stream of steam is injected into the first passdesalted crude oil in the form of steam bubbles that are quite largerelative to any salt particles or relative to the any small droplets ofbrine water so as to create steam bubbles that will have substantialcontact with the first pass desalted crude oil along with any nearbyremaining suspended salt particles and remaining water dropletsincluding any remaining brine droplets, such that a single steam bubblemay contact numerous salt particles and brine droplets. The steambubbles are then condensed into droplets of liquid water while at thesame time dissolve any remaining and available salt particles formingnew brine droplets and also delivering a portion of the water, asliquid, vapor or both, within steam bubbles into any remaining andavailable small brine droplets resulting in enlarged brine dropletshaving a size more amenable for separation from the crude oil. Theliquid water is then separated and removed from the first pass desaltedcrude oil where any dissolved salt goes with the separated water forminga twice desalted crude oil. The overall process is particularlycharacterized in that it does not include imposing high shear mixing ofuncondensed steam bubbles within the crude oil.

The invention more particularly relates to a process for removing saltfrom crude oil wherein the salt may be in the form of particles ofcrystalline salt suspended in the crude oil or as small droplets ofbrine water suspended in the crude oil, or both. The process includesinjecting steam into the crude oil in the form of steam bubbles that arequite large relative to any salt particles or relative to the any smalldroplets of brine water so as to create contact between the steambubbles and the crude oil along with any nearby suspended salt particlesand brine droplets where a single steam bubble may actually contactnumerous salt particles and brine droplets. The steam bubbles collapseand condense into droplets of liquid water while at the same timedissolving available salt particles creating new brine droplets and alsodelivering a portion of the water, whether liquid or vapor, within steambubbles into any available small brine droplets resulting in enlargedbrine droplets having a size more amenable for separation from the crudeoil. Thereafter, liquid water is separated from the crude oil where thewater includes salt dissolved therein. The process is particularlycharacterized in that it does not include imposing high shear mixing ofthe injected steam and further where the steam is injected into asteam-crude mixing zone against the direction of flow of the crude oilthrough the where the steam-crude mixing zone.

The invention more particularly relates to a process for removing saltfrom crude oil wherein the salt may be in the form of particles ofcrystalline salt suspended in the crude oil or as small droplets ofbrine water suspended in the crude oil, or both. The process includesinjecting steam into the crude oil in the form of steam bubbles that arequite large relative to any salt particles or relative to the any smalldroplets of brine water so as to contact the steam bubbles with thecrude oil along with any nearby suspended salt particles and brinedroplets, such that a single steam bubble may actually contact many saltparticles and brine droplets. The steam bubbles are condensed intodroplets of liquid water while at the same time dissolving availablesalt particles forming new brine droplets and also delivering a portionof the water, whether liquid or vapor, within steam bubbles into anyavailable small brine droplets resulting in enlarged brine dropletshaving a size more amenable for separation from the crude oil. Theliquid water is then separated and removed from the crude oil where theremoved water has salt that had been suspended in the crude oildissolved therein. The process is particularly characterized in that itdoes not include imposing high shear mixing of the injected steambubbles and wherein the steam injection occurs in a steam-crude mixingzone where crude oil flows through the steam-crude mixing zone in adefined direction of flow and the steam is injected at a low levelwithin the direction of flow.

The invention more particularly relates to a process for removing saltfrom crude oil wherein the salt may be in the form of particles ofcrystalline salt suspended in the crude oil or as small droplets ofbrine water suspended in the crude oil, or both. The process includesinjecting steam into the crude oil in the form of steam bubbles that arequite large relative to any salt particles or relative to the any smalldroplets of brine water so as to contact the steam bubbles with thecrude oil along with any nearby suspended salt particles and brinedroplets, such that a single steam bubble may actually contact numeroussalt particles and brine droplets. The steam bubbles collapse andcondense into droplets of liquid water while at the same time dissolvingavailable salt particles creating new brine droplets and also deliveringa portion of the water, whether liquid or vapor, within steam bubblesinto any available small brine droplets resulting in enlarged brinedroplets having a size more amenable for separation from the crude oil.Thereafter, the liquid water is separated from the crude oil such thatthe removed water includes salt dissolved therein. The process isparticularly characterized in that it does not include imposing highshear mixing of steam bubbles within the crude oil and also where thesteam is injected in a steam-crude mixing zone where crude oil flowsthrough a venturi tube and into the steam-crude mixing zone and steam isinjected to be drawn just downstream from peak flow rates of crude oilin the venturi to aggressively stir the steam bubbles into the crude oilbut not shear the steam bubbles.

The invention more particularly relates to a process for removing saltfrom crude oil wherein the salt may be in the form of particles ofcrystalline salt suspended in the crude oil or as small droplets ofbrine water suspended in the crude oil, or both. The process includesinjecting steam into the crude oil in the form of steam bubbles that arequite large relative to any salt particles or relative to the any smalldroplets of brine water so as to contact the steam bubbles with thecrude oil along with any nearby suspended salt particles and brinedroplets, such that a single steam bubble may contact numerous saltparticles and brine droplets. The steam bubbles are collapsed andcondensed into droplets of liquid water while at the same timedissolving available salt particles forming new brine droplets and alsodelivering a portion of the water, either as liquid or vapor or both,within steam bubbles into any available small brine droplets resultingin enlarged brine droplets having a size more amenable for separationfrom the crude oil. The liquid water is then separated from the crudeoil where the water contains the salt dissolved therein. The process isparticularly characterized in that it does not include imposing highshear mixing of the uncondensed steam bubbles and wherein the steam isinjected in a hydrocyclone steam-crude mixing zone where crude oil flowsthrough a tangential inlet of the steam-crude zone to create a vortexflow while the steam is injected into the axis of rotation of the crudeoil and stirred into the flow so that the steam bubbles are caused tocollide with many elements of the crude oil.

The invention more particularly relates to a process for removing saltfrom crude oil wherein the salt may be in the form of particles ofcrystalline salt suspended in the crude oil or as small droplets ofbrine water suspended in the crude oil, or both. The process includesinjecting steam into the crude oil in the form of steam bubbles that arequite large relative to any salt particles or relative to the any smalldroplets of brine water so as to contact the steam bubbles with thecrude oil along with any nearby suspended salt particles and brinedroplets, such that a single steam bubble may actually contact a numberof salt particles and brine droplets. The steam bubbles are condensedinto droplets of liquid water while at the same time dissolvingavailable salt particles forming new brine droplets and also deliveringa portion of the water, whether liquid or vapor, within steam bubblesinto any available small brine droplets resulting in enlarged brinedroplets having a size more amenable for separation from the crude oil.The liquid water is then separated from the crude oil where the removedwater includes the salt dissolved therein. The process is particularlycharacterized in that it does not include imposing high shear mixing ofthe injected steam bubbles with the crude oil and wherein the step ofinjecting the steam occurs in a steam-crude mixing zone where the steamis injected through an interface between two objects which are springbiased toward each other.

The invention more particularly relates to a process for removing saltfrom crude oil wherein the salt may be in the form of particles ofcrystalline salt suspended in the crude oil or as small droplets ofbrine water suspended in the crude oil, or both. The process includesinjecting steam into the crude oil in the form of steam bubbles that arequite large relative to any salt particles or relative to the any smalldroplets of brine water so as to contact the steam bubbles with thecrude oil along with any nearby suspended salt particles and brinedroplets, such that a single steam bubble may actually contact a numbersalt particles and brine droplets. A gas is injected into crude oil withthe steam bubbles therein to stir the crude oil and steam bubbles whilethe steam bubbles are condensing into droplets of liquid water. Whilethe steam bubbles are condensing they are contacting and dissolvingavailable salt particles creating new brine droplets and also deliveringa portion of the water, whether liquid or vapor, within steam bubblesinto any available small brine droplets resulting in enlarged brinedroplets having a size more amenable for separation from the crude oil.The gas is separated from the crude oil after the steam bubbles havecondensed and collapsed and thereafter the liquid water is separatedfrom the crude oil where the water takes the salt dissolved therein withit leaving desalted crude oil. The process is particularly characterizedin that it does not include imposing high shear mixing of the steambubbles with the crude oil to increase contact between steam and thesuspended salt.

The invention more particularly relates to a process for removing saltfrom crude oil wherein the salt may be in the form of particles ofcrystalline salt suspended in the crude oil or as small droplets ofbrine water suspended in the crude oil, or both. The process comprisesinjecting steam into the crude oil in the form of steam bubbles that arequite large relative to any salt particles or relative to any smalldroplets of brine water so as to create steam bubbles that will havesubstantial contact with the crude oil along with any nearby suspendedsalt particles and brine droplets, such that a single steam bubble maycontact numerous salt particles and brine droplets. A chemicaldemulsifier is added to the crude oil and a light gas is injected intothe crude oil with the steam bubbles to stir the steam bubbles with thecrude oil. The crude oil with the steam bubbles, chemical demulsifierand light gas is directed into a vertical flow chamber where the steambubbles condense into droplets of liquid water in the vertical flowchamber while at the same time dissolving available salt particles andalso delivering a portion of the water, whether liquid or vapor, withinsteam bubbles into any available small brine droplets resulting in newbrine droplets and/or enlarged brine droplets having a size moreamenable for separation from the crude oil. The light gas is separatedthe from the crude oil after the steam bubbles have condensed andcollapsed and the water droplets are coalesced in a static coalescermixer before the liquid water is separated from the crude oil. Theliquid water includes the salt dissolved therein. It should be notedthat the process is particularly characterized in that it does notinclude imposing high shear mixing of uncondensed steam bubbles withinthe crude oil to increase contact between injected steam or water andthe suspended salt.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete understanding of the present invention and benefitsthereof may be acquired by referring to the follow description taken inconjunction with the accompanying drawings in which:

FIG. 1 is schematic view of a conventional prior art system forsupplying crude oil into a refinery including a crude oil storage tankremote from the primary operational portion of a refinery, a prior artdesalting system and a charge pump and supply line to carry the crudeoil from the charge pump to the desalting system;

FIG. 2 is schematic view similar to FIG. 1 showing a first aspect of thepresent invention relating to adding steam to crude oil at or near thestorage tank that is well upstream of the desalting system to heat thecrude oil and reduce viscosity and drag for moving the crude oil intothe operational portion of the refinery and to aid in removing salt andother contaminants from the crude oil when it gets to the desaltingsystem;

FIG. 3 is schematic design showing a second aspect of the presentinvention comprising a steam desalting system;

FIG. 4 is a schematic view of a second embodiment of the steam desaltinginvention where the crude oil is first subjected to water injection andaggressive high shear mixing prior to injection of steam;

FIG. 5 is a schematic view of a third embodiment of the steam desaltinginvention where the crude oil receives water and aggressive high shearmixing, but is first subjected to steam where the steam is allowed tocondense and the steam bubbles to fully collapse before the aggressivehigh shear mixing;

FIG. 6 is a schematic view of a fourth embodiment of the steam desaltinginvention where the crude oil is subject to two desalting stages whereeach stage is accomplished using steam and no aggressive high shearmixing;

FIG. 7 is a schematic view of a fifth embodiment of the steam desaltinginvention where the crude oil is subject to two desalting stages and thefirst stage is accomplished using steam and no aggressive high shearmixing and the second stage includes water injection and aggressive highshear mixing;

FIG. 8 is a schematic view of a sixth embodiment of the steam desaltinginvention where the crude oil is subject to two desalting stages and thefirst stage is accomplished using injected water and aggressive shearmixing while the second stage is accomplished with steam and noaggressive high shear mixing;

FIG. 9 is a schematic view of a seventh embodiment of the steamdesalting invention where the crude oil is subjected to two desaltingstages and receives water and aggressive high shear mixing in the firststage, but is first subjected to steam where the steam is allowed tocondense and the steam bubbles to fully collapse before the aggressivehigh shear mixing which is then followed by a second stage of steamdesalting with no aggressive high shear mixing;

FIG. 10 is a schematic view of an eighth embodiment of the steamdesalting invention where the crude oil is subjected to two desaltingstages and the crude oil receives water and aggressive high shear mixingfirst followed by steam injection where the steam is allowed to condenseand the steam bubbles to fully collapse before the gravity separatorfollowed by a second stage of steam desalting with no aggressive highshear mixing;

FIG. 11 is a schematic view of a ninth embodiment of the steam desaltinginvention where the crude oil is subjected to two desalting stages andreceives water and aggressive high shear mixing in the first stage, butis first subjected to steam where the steam is allowed to condense andthe steam bubbles to fully collapse before the aggressive high shearmixing and gravity separation followed by a second stage comprisingwater injection and aggressive high shear mixing with gravityseparation;

FIG. 12 is a schematic view of a tenth embodiment of the steam desaltinginvention where the crude oil is subjected to two desalting stages andreceives water and aggressive high shear mixing first in the first stageand is then subjected to steam injection where the steam is allowed tocondense and the steam bubbles to fully collapse before gravityseparation which is then followed by a second stage comprising waterinjection and aggressive high shear mixing with gravity separation;

FIG. 13 is a schematic view of an eleventh embodiment of the steamdesalting invention where the crude oil is subjected to two desaltingstages and receives steam injection where the steam bubbles are allowedto condense and fully collapse before gravity separation and in thesecond stage has water injected with aggressive high shear mixing beforesteam is injected and allowed to condense and the steam bubbles allowedto fully collapse before gravity separation;

FIG. 14 is a schematic view of a twelfth embodiment of the steamdesalting invention where the crude oil is subjected to two desaltingstages and receives steam injection where the steam bubbles are allowedto condense and fully collapse before gravity separation and in thesecond stage has water injected with aggressive high shear mixing aftersteam has been injected and allowed to condense and the steam bubblesallowed to fully collapse before the aggressive high shear mixing;

FIG. 15 is a schematic view of a thirteenth embodiment of the steamdesalting invention where the crude oil is subjected to two desaltingstages and receives water and aggressive high shear mixing in the firststage, but is first subjected to steam where the steam is allowed tocondense and the steam bubbles to fully collapse before the aggressivehigh shear mixing and gravity separation and similarly in the secondstage has water injected with aggressive high shear mixing after steamhas been injected and allowed to condense and the steam bubbles allowedto fully collapse before the aggressive high shear mixing and gravityseparation;

FIG. 16 is a schematic view of a fourteenth embodiment of the steamdesalting invention where the crude oil is subjected to two desaltingstages and first receives water and aggressive high shear mixing in thefirst stage followed by steam injection after the aggressive high shearmixing where the steam is allowed to condense and the steam bubbles tofully collapse before the gravity separation and similarly in the secondstage has water injected with aggressive high shear mixing before steamis injection is injected and allowed to condense and the steam bubblesallowed to fully collapse before the gravity separation;

FIG. 17 shows a lance type steam injector directing steam against thedirection of flow of crude oil entering the steam-crude mixing zone;

FIG. 18 shows a lance type steam injector directing steam into the flowof steam in the steam-crude mixing zone where the steam is directed intoa generally horizontal flow of crude oil;

FIG. 19 is a schematic view of a shower head steam injector comprising aplurality of small apertures for injecting steam against the directionof flow of the crude oil into the steam-crude mixing zone;

FIG. 20 is a schematic perspective view of an ironing table tip steaminjector in a low portion of the steam-crude mixing zone with crude oilflowing generally horizontally while steam is injected at the lowerportion through a generally flattened steam head with a great pluralityof steam apertures to deliver steam bubbles into the crude oil;

FIG. 21 is schematic view of a venturi type steam injector for injectingsteam into crude oil as it enters the steam-crude mixing zone;

FIG. 22 is a schematic perspective view of a hydrocyclone steam injectorfor injecting steam into crude oil where the oil flow is rotating withinthe steam-crude mixing zone;

FIG. 23 is a schematic elevation view of another alternative injectorfor injecting steam into crude oil comprising a spring biased stopperand bell shaped tube working together to squeeze steam into thesteam-crude mixing zone;

FIG. 24 is a schematic elevation view of an additional alternativeinjector for injecting steam into crude oil comprising a pair of cymbaltype plates spring biased together for squeezing steam into asteam-crude mixing zone;

FIG. 25 is a schematic view of another embodiment of the presentinvention where steam along with at least one process chemical are addedto the oil to remove salt and other contaminants and where the processchemicals enable the condensed steam to better coalesce and be morecompletely removed from the crude along with the dissolved salts;

FIG. 26 is a schematic view of a further alternative embodiment of thepresent invention where steam and light hydrocarbon gas is added to thecrude oil and the light gas aids in the coalescing of the condensedsteam as water droplets combine into larger water droplets for easierand more complete separation in the gravity separator;

FIG. 27 is a schematic view of an alternative arrangement for thesteam-crude mixing zone where the flow of crude oil with the steam flowdownwardly insuring that steam bubbles have fully condensed andcollapsed before entering the gravity separator;

FIG. 28 is a schematic view of an alternative arrangement for thesteam-crude mixing zone similar to the embodiment shown in FIG. 27 butwhere the crude oil and the steam added flow upwardly insuring thatsteam bubbles have fully condensed and collapsed before entering thegravity separator;

FIG. 29 is a schematic view of an alternative arrangement for desaltersystem where after the steam-crude mixing zone, crude oil flows across acoalescer mixer to help cause water droplets to coalesce prior toentering the gravity separator;

FIG. 30 is a schematic view showing that many aspects of the presentinvention may be combined into an operating crude oil desalter systemaccording to the present invention where a venturi type injector may beoperated with light gas agitation and a coalescer;

FIG. 31 is another schematic view showing the system presented in FIG.30 with water injection and aggressive high shear mixer downstream ofthe steam-crude mixing zone but upstream of the coalescer mixer; and

FIG. 32 is another schematic view comparable to FIG. 31 showing thedesalter system presented in FIG. 30 with water injection and aggressivehigh shear mixer upstream of the steam injection.

DETAILED DESCRIPTION

Turning now to the detailed description of the preferred arrangement orarrangements of the present invention, it should be understood that theinventive features and concepts may be manifested in other arrangementsand that the scope of the invention is not limited to the embodimentsdescribed or illustrated. The scope of the invention is intended only tobe limited by the scope of the claims that follow.

Referring to FIG. 1, a prior art desalter system 10 is shown forremoving salt from crude oil being brought in from crude oil storagefacilities and delivered to the operational portion of a refinery. Forillustration purposes, the crude oil is shown to be stored in a largestorage tank 12. Crude oil is drained from a lower portion of the tank12 through a line 13 an fed to a charge pump 14 which directs the crudeoil from the storage facilities through a conduit 15 and ultimately to afirst refining vessel 40 in a refinery. As noted above, crude oils withdifferent characteristics are conventionally blended in preparation forrefining which can occur in a blend tank similar to tank 12 or bydelivering crude from a number of storage tanks similar to tank 12 intoa common pipe for in-line blending. This is all typically done in thetank farm which is usually quite some distance from the operationalportion of the refinery. The crude is typically heated by variousdifferent known means as it passes to vessel 40. The first vessel 40 islikely to be a furnace for a fractionation tower where crude oil isheated and then separated into its fractions based on differing boilingtemperatures of each of the fractions.

Focusing now on the desalter system 10, it is desired to remove saltfrom the crude to reduce fouling in the refinery and corrosion to thevarious units in the refinery including the first refining vessel 40. Toremove salt and contaminants, it is conventional to inject water (about2% to 10% by weight, water to crude) into the crude oil flowing throughconduit 15 via the first water feedline 16. Water being injected intothe crude oil via the first water feedline 16 creates reasonably largedroplets of water in the crude oil as the water is immiscible in crude.To enhance salt transfer into the injected water, the water and crudeoil are passed through a high shear mix valve 17 that aggressively mixesthe water with the crude shearing the larger droplets into much smallerwater droplets. The smaller droplets have a much higher surface areathan the larger droplets to create a very high contact area with thesalt in the crude oil, and the turbulence associated with the mixingcreates high velocity collisions between the water droplets and salt inthe crude oil. These two actions get the water to quickly accumulatesalt, but this is only the first function of the desalter. The desalterneeds to separate as much water as possible removed back out of thecrude oil, including the now salty water so that the crude oil may moveon to be refined without compromising the operations of systems withinthe refinery. Appreciable water in the crude oil causes numerouscomplications and challenges for a number of systems and must be removeddown to a very low concentration. To remove the water droplets from thedesalted crude oil, the mixture is directed into a settling tank 20where the crude oil rises and the water droplets settle. These tankstend to be quite large themselves to allow time and space for the waterdroplets to settle to the bottom where it is removed at drain 21 whilethe now cleaner crude is removed via line 22.

Continuing with the description of a conventional prior art desaltersystem 10, it is common to use two successive stages. In the secondstage, the somewhat desalted crude oil again receives a minimal waterinjection via second injection feedline 26, aggressive high shear mixingacross the mix valve 27 and a second stage of settling in the secondsettling tank 30. From the second settling tank 30, water exits viadrain 31 which may have only captured a small amount of salt from thecrude oil in the second stage so may be recycled to feed the first waterfeedline 16. The twice desalted crude exits the second settling vessel30 via line 32 which is then delivered to the first refinery unit 40.

It is conventional in crude oil desalter systems like the one shown inFIG. 1 to create rather stable emulsions of crude oil and water withinthe settling tanks 20 and 30. As such, it is common practice to addemulsion breakers to the crude oil to reduce the volume of emulsion andenhance the separation of water (including salty water) from the crudeoil. In the present invention, performing some or all of the salttransfer from the crude oil into steam versus into liquid water hasshown remarkable advantages for desalting crude oil and, whenimplemented in an advantageous arrangement, may significantly reduce theproduction of stable emulsions. This means that water is less likely tobe bound up with the crude oil in a manner in which the crude oil is notsuitable for refining. And while it is necessary to keep water fromgoing into the refinery, it is also very important to keep hydrocarbonsfrom going out with the water as hydrocarbons tend to be toxic to themicroorganisms in waste water treatment operations.

A comparison of salt transfer into steam versus into water was performedrecognizing that there are a number of variables that are present ineach arrangement that are not present in the other. Using a laboratoryscale steam injector with a sample of crude oil having a known saltcontent, measurements were undertaken of the droplets of water formed bythe condensing and collapsing steam bubbles. Using the size of thedroplets that were measured, water was added to another sample of thesame crude oil and the high shear mix valve was adjusted to createdroplets of the same size. Both systems were fed the same emulsionbreaker, had the same temperature entering the settling tank and themeasured salt transfer for steam droplets was measured to capture 95% ofthe salt content while the comparable water droplets captured 66% of thesalt content. While this is appealing, it should also be appreciatedthat a steam desalter at its optimal operating settings may produce alarger water droplet size while still capturing a higher percentage ofthe salt thus making the water easier to separate from the crude oilwhere each component has less content of the other at the outlet fromthe gravity separation vessel. And there are a number of ways that thismay be implemented.

In a first implementation of the present invention, it is shown as animprovement to a conventional system such as the one shown in FIG. 1.So, referring now to FIG. 2, water in the form of steam may be added tothe crude not in the desalter system 10, but rather well away from thedesalter system 10. Since steam will heat the crude oil while alsocapturing salt, the heat value of the steam may be used to reduce theeffective viscosity of the crude oil. A reduced viscosity reduces theresistance to flow in the conduit 15 coming from the storage vessel 12.So, as shown in FIG. 2, a steam production system 50 is shown to providesteam at one or more selected locations between the crude tank 12 andthe desalter system 10. Steam is often available in refineries, but forpurposes of explanation, a steam production system 50 creates steam andis installed to deliver the steam to the location or locations desired.Considering the options, the earlier the steam is provided to the crude,the easier it is to move the crude though the piping. However, it shouldbe recognized that delivering steam into a tank farm that is probablyquite some distance from the steam production system and the desalterwill present some logistical challenges. As such, the delivery of steamat a great distance may be limited or impractical, but even if added tothe steam half way to the desalter could reduce friction over thatdistance and may make the lower viscosity of heated crude valuableenough to justify the engineering and construction to get steam out to amidway point. So, as shown by arrow 51, the steam may be delivered tothe crude oil coming from the crude tank into line 13 upstream of thecharge pump 14. Having the steam injected at this point reduces the workload on the charge pump 14 as pumping lower viscosity crude oil does notrequire the same amount of energy to deliver the same volume of crude tothe same location at the other end of the conduit 15. The steam shouldcapture some salt into the condensing steam (water) and be separatedfrom the crude oil in the desalting system 10.

It should be noted that refineries and most industrial systems aredesigned to use high pressure and high temperature steam in variousprocesses, but once the steam is cooled and obtains a lower pressuredownstream of the processes for which the steam system is designed, itis often termed waste heat or waste steam. This invention may actuallyprovide a really good use of such low value steam regardless of how muchvalue it can deliver to a refinery by more effectively and moreefficiently removing salt and contaminants that are troublesome innumerous places within refinery systems.

Even if the steam is injected downstream of the pump but within theconduit 15 out in or near the tank farm (including and in the vicinityof tank 12) as shown by arrow 52, the friction created by the crude oilin conduit 15 is reduced. As such, the charge pump 14 would stillrequire less energy to deliver the same amount of crude to the desaltersystem 10.

Turning now to FIG. 3, a simplified system 110 is shown to remove saltutilizing one of the principle tenets of the invention and that beingusing stream bubbles to contact and transfer salt suspended in crude oilrather than liquid water. Expanding on this point, it is believed thatthe mechanism for water droplet growth and especially growth ofexceptionally small brine water droplets occurs differently for steamthan for water. In a conventional water washing system, the watercontent of the crude oil coming into the desalter is generally less thanabout 0.2 percent by weight water to oil. It is also believed that mostof the salt is bound up within this small water content in the form ofremarkably small water droplets that are generally less than a micron indiameter. These salt bearing microdroplets or brine water droplets tendto include a relatively thick and hardened hydrocarbon coating or shellsurrounding the droplet. This hardened coating is formed of highmolecular weight large hydrocarbon molecules like asphaltenes thatgenerally seal off the micro sized brine water droplets from other waterdroplets.

It is believed that current techniques for removing salt dispersed incrude oil are successful are because of high velocity collisions betweenwater droplets and micro brine water droplets that crack or penetrateany fissures in the coating that results in a larger brine droplet thateffectively sheds away any remaining portions of the brittle shell orcoating. So, this process requires significant kinetic energy to removesalt, but also must use a minimal volume of water recognizing thatresidual water in the crude oil after the crude oil has been desalted isalso a problem in the refinery. As such, it is typical to limit theamount of water added to the crude in a desalting operation to about 5%to 10% by weight water to crude oil. In using steam, the same upperlimits probably apply on a weight basis, but it is expected that thelowest amount of water in whatever physical state will be used toeffectively remove the optimum amount of salt. It is believed that arange of about 1% to 8% is the most likely range, but less than about 6%is most likely to be used. Substituting in the maximum volume of steamto replace liquid water as practical given temperature limits to heatingthe crude seems most optimal and getting at least 2% steam by volume isdesirable and better yet, at least 4% steam by weight of the crude oilis the most desirable.

The high kinetic energy is created by aggressive mixing in a high shearmixer. As the wash water is added, it gets shredded into droplets ofbetween 20 to about 40 microns in size. Due to the small size of thebrine droplets, they are not shredded in the same way by the high shearmixing or even so much as peel the shell or coating off these small saltcontaining droplets. But the aggressive high shear mixing causes thewash water droplets and brine droplets to undergo violent and turbulentcollisions within the crude oil that is able to at least begin theprocess of removing the shell and growing the microdroplets intodroplets of a size more amenable to separation. Once a micro brinedroplet has coalesced with a wash water droplet and attained a largersize, it is then more available for coalescing with other waterdroplets. However, any micro brine droplet with a coating still intactis much less likely to coalesce with other droplets downstream of theviolent turbulence of the high shear mixer. Steam bubbles do not seem toneed this high velocity collision with a brine microdroplet to coalesceor grow the microdroplet.

There are a number of factors that increase or reduce the probability oftwo water droplets to coalesce including temperature, droplet size,relative velocity and the viscosity of the medium. The interfacialtension within each droplet can also resist coalescing, especially forreally small droplets. The existence and integrity of hydrocarbon shellsreally reduces the likelihood of brine droplets from coalescing withdroplets of wash water droplets without some force or action topenetrate or compromise the shell.

Steam bubbles seem to grow brine microdroplets by both heating and bymore broadly surrounding or contacting brine microdroplets. Vaporouswater molecules in steam are able to penetrate through fissures in thehard coating described above that may be inherent or may be enlarged bybeing heated. Moreover, with the substantial size of steam bubbles andthe more amorphous and pliable outer surface of a steam bubble comparedto a water droplet, more of the surface area and more fissures of eachbrine microdroplet is exposed to and contacted by the steam bubble forabsorbing or accreting water (whether vapor or liquid) into and growingthe microdroplets. An enlarged microdroplet thereafter will have largerfissures for the steam bubble to more rapidly deliver steam and waterinto the microdroplets further compromising any seal on the microdropletof the hydrocarbon shell.

It is worth noting that a single bubble of steam may contact manymicrodroplets due to the fact that even a small steam bubble of a fewmillimeters in diameter is profoundly larger than a microdroplet. And,it is more likely that steam bubbles will have a maximum size that islarger than a few millimeters. Ideally, the steam bubbles will have aninitial size of a half centimeter up to tens of centimeters in diameter.However, measuring steam bubbles size is quite a challenge as each steambubble first quickly expands and then quickly shrinks by condensation asit cools from its first contact with the crude oil and whatever issuspended in the crude oil. Observations suggest the steam bubbles arefully condensed in well less than a full second after first emanatingfrom the steam delivery system into a water droplet having about onethousandth of the volume of a steam bubble. Typically, a steam bubblecondenses to a single water droplet, but as the steam droplet contactshydrophilic elements in the crude oil (crude oil is well known to behydrophobic) such as crystalline salt and other droplets of water, someof the water content of the steam bubble is released to or contributedto or transferred to those elements. A steam bubble may actuallycoalesce with one or several of these elements such that a separate andindividual water droplet from that steam bubble may not be created. Thefewer (and therefore larger) water droplets created suggest a higherrate of removal of water from the crude oil in the gravity separator,which is highly desired.

It is noted that not only may one steam bubble likely grow multipledroplets, but that a single brine droplet may also grow pursuant tocontacts with a number of different steam bubbles. The result is largerdroplets with much diminished coatings that are more amenable to gravityseparation, not only on their own, but these enlarged and unsealeddroplets are also more amenable to gravity separation by additional andsubsequent coalescing with other droplets in the system.

Returning now to FIG. 3, a most simplified version of the inventionshowing that that liquid water is not provided into the desalting system110. Water, only in the form of steam is provided. A steam productionsystem 150 provides steam through a steam delivery system 155 to asteam-crude mixing zone 160 which may be a vessel or chamber or thelike, but may be a portion of a pipe. The steam-crude mixing zone 160may simply be a portion of the conduit or pipe 115 via which crude isdelivered to the desalting system 110 on the way to the first refiningvessel 140 in the refinery or it may be a vessel designed to permit thesteam bubbles to yield their heat to the crude oil and fully condense.The steam-crude mixing zone 160 may take other forms as will beexplained below. Within the steam-crude mixing zone 160, all of thesteam bubbles are intended to be condensed and collapsed into liquidwater droplets and then delivered by line 161 into gravity separator120. Gravity separators are conventional for desalter systems where thewater sinks to the bottom and is released to waste water treatment viadrain 121 while crude exits at the top of the separator via line 122 tobe carried into first refining vessel 140.

Since steam is more amenable to coalescing with microdroplets of brine,creating high velocity collisions is not as necessary. As such, as shownin FIG. 3, steam is injected, but there is no high shear mixing valve.The steam is injected into the crude oil conduit 115 in a variety ofarrangements with the intention of creating an army of steam bubbles tocapture salt and also to increase the temperature of the crude oil to anoptimum temperature for operation of the gravity separator 120. By ruleof thumb but within limits, warmer crude oil is less viscous and watershould separate from warmer crude by settling at a faster rate. Thereare perceived optimum temperatures at which a gravity separator is tooperate and there are a number of conventional methods to get the crudeoil to that temperature. A lot of effort and planning goes into heatmanagement within a refinery and using heat exchangers to heat the crudeoil is conventional. As such, in accordance with the invention, thesteam injection shown in FIG. 3 would be expected to operate in a mannerthat optimizes the temperature of the crude oil and water mix going intoseparator 120. Moreover, while gravity separation is preferred, otherdensity based separation technologies are within the scope of theinvention.

Recognizing that in some refineries, an unlimited volume of steam maynot be added to the crude oil as the crude could exceed the desiredtemperature range, FIG. 4 shows an arrangement that employs an injectionof steam, but also utilizes some level of conventional water washing ofthe crude oil. In this arrangement, water is added first to the crudeoil conduit 215 via water feedline 216. The wash water and crude oilundertake aggressive high shear mixing at high shear mix valve 217.After the aggressive high shear mixing, steam from steam productionsystem 250 delivers steam into steam-crude mixing zone 260 via steaminjection system 255. As with the embodiment shown in FIG. 3, all of thesteam bubbles are allowed to fully condense before the crude oil andwater is taken into gravity separation tank 220. In this arrangement,the steam bubbles tend not only to capture crystalline salt and grow themicrodroplets of brine water, but also coalesces or feeds water into anyof the salty water droplets created by the wash water droplets whetherthey have pulled brine droplets into them or not. Either way, the steambubbles help render the water more amenable for gravity separation.Again, like in the previous embodiment, salty water exits the gravityseparator 220 via drain 221 while desalted crude oil exits through line222 to be taken into the first refining vessel 240.

In a simple alternative to the embodiment shown in FIG. 4, the nextembodiment is shown in FIG. 5 where the desalting system 310 providesthe steam addition first from steam production system 350. Steam bubblesare added to the crude oil in steam-crude mixing zone 360 via steaminjection system 355. The crude oil is heated by the steam additionwhile the steam grows the microdroplets of brine water and condensesinto water droplets. Additional water is added after the steam has fully(or nearly fully) condensed via wash water feedline 316. The crude oilwith the wash water, water droplets from condensed steam and enlargedbrine droplets then goes through the high shear mixing valve 317 tocreate the high energy collisions between water droplets and brinedroplets to grow the brine droplets. The mixture of crude oil and waterand salt is then gravity separated in gravity separator 320 where saltywater is drained via drain 321 while the desalted crude oil exitsthrough line 322 to proceed to the first refining vessel 340. In thisarrangement, an interesting benefit may occur even for microdroplets ofbrine where the steam may soften or thin the hydrocarbon shell orcoating on the microdroplets of brine making them more vulnerable inhigh shear mixing. As such, the conventional portion of this arrangementmay actually become more efficient at coalescing with brine dropletswith some thickness of the coating intact after the steam-crude mixingzone 360.

Turning to more complicated arrangements of the present invention, it isnoted that in many refineries, multiple stages of desalting occur. Thepresent invention includes arrangements to take advantage of a secondopportunity to remove salt and provide the refinery with considerablylower salt content. Before describing a multiple stage system, it shouldbe understood that steam really does provide an advantaged system forcapturing salt. Comparative tests are not easy to set up to do applesfor apples comparisons. With a view toward trying to create as close toapples to apples comparisons, a test system was set up for injectingsteam into a stream of crude oil with known salt containing properties.A similar system using wash water and a high shear mix valve was alsoset up. The water droplets emanating from steam injection were measuredjust downstream from the steam-crude mixing zone and found to be about80 microns. The mix valve for the wash water system was adjusted untilconsistent measurements of the water droplets downstream of the mixvalve also measured about 80 microns. The same crude oil was run in eachsystem at the same rate with equal amounts of a known and conventionalemulsion breaker. The sample of crude oil having been steam desalted wasfound to have about 5% of the original salt content remaining in thecrude oil after one pass. The sample of the same crude having beensubjected to the wash water and high shear mixing was found to haveabout 34% of the original salt content under the pertinent operatingconditions. However, it should be pointed out that while this was anattempt to create apples to apples data, this does not suggest that thisis a comparison of optimal to optimal arrangements. It may be that moresalt may be removed from the crude oil if the mix valve is set at a moreaggressive setting creating smaller wash water droplets and more violentturbulence. That may include a concern about removing salt at theexpense of higher water content in the crude going into the refinery. Italso does not suggest that the steam injection used for this comparativetest was optimal either. But, the comparison does clearly suggest thatconsiderable advantage may be obtained by properly injecting steam intocrude oil for desalting purposes.

Turning back to the embodiment of the present invention shown in FIG. 6,the crude oil is subjected to two stages of steam injection where eachstage includes gravity separation. While additional steam may beinjected from additional injection systems, it is considered a singlestage if all the steam is allowed to condense and then the water andcrude oil are separated.

In this arrangement, the desalter system 410 comprises a crude oilconduit 315 delivering crude oil into first steam-crude mixing zone 360where the steam bubbles heat the crude and do their work making the saltmore amenable to removal at the first gravity separator 320. Steam isprovided from the steam production system 450 and delivered to the firststage via steam injection line 455. Salty water is drained from thegravity separator 320 by drain 321 while crude oil that may becharacterized as first pass desalted crude oil passes out of the firstgravity separator 320 via line 322 and passed to the second steam-crudemixing zone 365. The first pass desalted crude is again subjected tosteam which both heats the crude oil and renders more of the residualsalt content amenable to gravity separation. Like the other embodimentsthe mix of crude oil and salty water are gravity separated in secondstage gravity separator 330 where salty water is drained at drain 331while the second pass desalted crude oil is passed on to the firstrefinery vessel 440.

It should be recognized that two stages of steam may overheat the crudeoil relative to optimal temperature of the gravity separators so anotherembodiment of the present invention is envisioned where wash water isused in the second stage assuming that the crude oil will retain much ofits heat from the first stage. So, in the embodiment shown in FIG. 7,the desalting system 510 includes a steam production system 550, a steamdelivery line 555 provides steam to the steam-crude mixing zone tofollow a process similar to that which has been previously described.The first pass desalted crude oil is then subjected to conventional washwater desalting to remove residual salt. It should be noted that theconventional wash water desalting may be optimally operated to create adifferent size water droplets considering the effectiveness of saltremoval in the first stage and the desire not to leave much water in thecrude oil entering the refinery. Small water droplets tend to be harderto separate in the gravity separator and with the view that only a smallresidual amount of salt remains, the mixing might be a little lessaggressive than in other installations.

Recognizing that a refinery may already have two stages of desalting,but a limited temperature tolerance for converting all of the desaltingwater to steam desalting may suggest leaving the wash water desalting inthe first stage as shown in FIG. 8 where the system 610 includes a washwater feedline 616 and high shear mixer 617. Knowing that steam will beused in a second stage that is able to coalesce with small droplets ofwash water, a refinery operator may set the first stage high shear mixvalve to an extra aggressive setting. While the average droplet sizemight be smaller going into the first stage gravity separator 620, thewater content of the first pass desalted crude oil will be reduced bygravity separation and the steam will be most effectively used tocoalesce with all of the water droplets whether salty or otherwise.Again, the water is removed by gravity separation in second stagegravity separator 630 before the twice desalted crude oil is deliveredto the first refinery vessel 640. It should also be noted that gravityseparation is the conventional technique for separating water from oil,but other techniques for separating water from oil would also be usefuland not outside the scope of the present invention.

Gravity separation vessels tend to be rather large. While they areinsulated, it is conceivable that heat may be lost and the temperaturemay be restored in a second stage by additional steam. In anotherembodiment shown in FIG. 9 where the desalting system 710 is arranged totake advantage of an opportunity to further inject steam to mosteffectively desalt the crude oil, steam is injected to the crude oilarriving from the tank farm via crude oil conduit 715 at steam-crudemixing zone 760. After all or virtually all of the steam bubbles(preferably all) have condensed, the wash water is added by wash waterfeedline 716 and the mixture is subjected to aggressive high shearmixing in high shear mixer 717. Water is removed by gravity separator720 and additional steam is added at the second stage steam-crude mixingzone. It is again noted that with the steam injection downstream of thehigh shear mix valve 717, the setting of the high shear mixer 717 may beset to a more aggressive setting than in a conventional desalter systemrecognizing that the steam addition in the second stage is there toprovide additional coalescence to the water droplets in the crude oilmaking the second stage gravity separator 730 more effective fromremoving water droplets that were sheared to a smaller size.

The embodiment shown in FIG. 10 is a variation from the embodiment shownin FIG. 9 where the crude oil is subjected to wash water injection firstat water injection feedline 816 and aggressive high shear mixing at highshear mixer 817 followed by steam injection. In this arrangement, thehigh shear mixer may be set to a very aggressive setting shearing thewash water droplets and creating exceptionally high turbulence intendingto get the benefit of many, many violent collisions knowing that twosuccessive steam injection steps will occur downstream. This means thateven if the wash water droplets are exceptionally small, the likelihoodthat the vast majority of wash water droplets will be coalesced with oneor more steam bubbles and grow back to a size that is amenable togravity separation. There is an appeal to this arrangement in that theshells on the brine droplets are being attacked both kinetically and bysteam in a manner that takes great advantage of the highest possibleturbulence practical. Again, the steam is added at steam-crude mixingzone 860 where all the steam bubbles fully condense and collapse beforeentering the first stage gravity separator 820, a second stage of steamis added at second stage steam-crude mixing zone 865 and further gravityseparation is accomplished in second stage gravity separator 830. Thesteam is supplied by steam production system 850 which is delivered bysteam injection lines 855 and 856.

It may be that a refinery may be determined to best take advantage ofsteam injection for salt removal by getting the heat into the crude oilearly in the process and then using water as a supplemental means ofsalt removal once the highest desired crude oil temperature has beenattained. That situation is shown in the next embodiment of theinvention in FIG. 11 where the desalting system 910 delivers steam intothe crude oil from steam production system 950 via steam injection line955 to the steam-crude mixing zone 960. The first stage includes liquidwater injection via feedline 916 along with aggressive high shear mixingat high shear mixer 917 before the first stage gravity separator 920. Asecond stage is shown with water injection feedline 926 and high shearmixer 927 and a second stage gravity separator 930.

In a hybrid of the prior described embodiments, a two stage salt removalsystem 1010 of the present invention is shown where the steam isinjected downstream of both the first liquid water feedline 1016 and thehigh shear mixing valve 1017. The steam is added early to the system toget the crude oil heated prior to the first stage separator 1020, but,as described above, the first stage high shear mixer may be set to amore highly aggressive setting with the steam injection just downstream.This embodiment works very similar to the other described systems wherethe gravity separator 1020 yields a first pass desalted crude via line1022 for the second stage desalting and in the second stage, water isadded via water feedline 1026 and aggressive mixed at high shear mixer1027.

FIG. 13 shows another variation of the invention where the salt isremoved in a two stage desalting system 1110, but where steam is addedat the beginning of the desalting process and again at the end. Thefirst addition of steam may operate to raise the crude oil temperatureto the highest desirable temperature to allow the steam to capture asmuch salt at steam is able and then let the salty water escape from thecrude in the first stage gravity separator 1120. However, to the extentthat high shear mixing is able to remove more of the brine, water isadded in the second stage at feedline 1126 and aggressively mixed athigh shear mixer 1127. Additional steam is provided after the high shearmixer 1127 at the second stage steam-crude mixing zone 1165 and, aspreviously discussed, the setting for the high shear mixer may be set alittle extra aggressively with the second stage steam injectiondownstream to use steam bubbles to coalesce all of the water dropletssuspended in the crude oil.

The embodiment shown in FIG. 14 is a slight variation to the embodimentshown in FIG. 13, but this is still an arrangement that may find use inan existing refinery where faith in the conventional technology of washwater and high shear mixing is much higher than steam addition. In thisarrangement, steam is added in a first stage alone without wash waterand high shear mixing. The steam is added at steam-crude mixing zone1260 such that all of the steam bubbles are allowed to condense andcollapse before the first stage gravity separator 1220. Steam is againadded in the second stage at steam-crude mixing zone 1265 and the crudeis finally subjected to the old reliable wash water and high shearmixing as shown with water feedline 1226 and high shear mixer 1227.

In still yet another embodiment of the present invention, a steamdesalter system 1310 is shown in FIG. 15 where two successive stages arearranged in essential duplication where each stage gets steam injectionfirst where the steam bubbles are allowed to condense and collapsebefore water and high shear mixing are accomplished. This arrangementwill be desirable when a steam only system would overheat the crude, butit is desired to contact salt crystals and brine microdroplets in eachstage.

In a variation of the embodiment shown in FIG. 15, another embodiment isshown in FIG. 16 where the steam desalter system 1410 includes twostages that are again duplicates of one another, but where the waterinjection and high shear mixing occurs before the steam injection. So,in this embodiment, water is injected from feedline 1416 and the crudeand water mixture are subjected to aggressive high shear mixing at thehigh shear mixer 1417. This is followed by the steam injection atsteam-crude mixing zone 1460. With the steam addition following the highshear mixing, the aggressiveness of the high shear mixing may be alteredto be more aggressive. Again, gravity separator 1420 provides first passdesalted crude oil via line 1422 while salty water is removed via drain1421.

Turning now to getting the steam to disperse into the crude oil and toefficiently remove contaminants turns out to be a rather un-simple task.Basically, steam does not easily mix with the crude. Steam is far lessdense than the crude and quickly moves through the crude oil. If poorlydispersed steam gets to the wall of the steam-crude mixing zone, it mayform a stagnant steam cavity within the system which would reduce theefficiency of salt extraction by reducing the interaction of the steambubbles with the suspended salt. A second risk for poorly dispersingsteam in the crude oil is if a steam bubble were to pass into thegravity separator which is intended to operate in a quiescent regime.Steam bubbles are very disturbing to quiescent regimes.

So, recognizing that as steam blends with the crude oil, it formsbubbles that tend to expand quickly (moving from a high pressuredelivery system to a lower pressure crude oil pipe), orienting the steamdelivery device into the crude oil to make sure the steam bubblescondense within the crude and away from pipe walls and vessel wallswould tend to optimize the advantages described above. In FIG. 17, crudeoil enters a the steam-crude mixing zone 1560 via conduit 1515 flowingin a direction indicated with the letter “F” where the steam-crudemixing zone 1560 is simply a section of the pipe constituting both. Inother embodiments described below, the steam-crude mixing zone is adistinct vessel. Steam is injected via feedline 1555 via steam port 1570that is inside the steam-crude mixing zone 1560 oriented in oppositionto the flow of the crude oil F. The steam bubbles 1571 are dispersedwithin steam-crude mixing zone 1560 with time and space to give up theirheat and condense and collapse to liquid water before contacting theside or outer walls of the pipe. Studies of the steam bubbles in crudeoil suggest that they collapse within a second of emerging from the port1570 of the steam injector 1555 and typically within about a tenth of asecond. At the same time, the crude oil is typically not in laminar flowbut rather has vortices and eddies and turbulence. Steam is delivered ata pressure of between 25 psi and 450 psi depending on the source of thesteam and perhaps other uses in heat exchangers and the like prior tobeing injected into the steam-crude mixing zone 1560. The pressure andvelocity of the steam passing through the feedline 1555 is sufficientlyhigher than pressure and velocity of the crude oil in conduit 1515 tokeep crude from entering the steam port 1570. The steam bubbles expand,cool and then collapse to liquid water droplets before exiting thesteam-crude mixing zone 1560.

Turning now to FIG. 18, another embodiment of the steam port is shown at1670 where steam is injected into the lower portion of the steam-crudemixing zone 1660. The port extends into the mixing zone to a distance toreduce the likelihood of a steam bubble proceeding directly to the wallof the steam-crude mixing zone 1660 before it would fully condense. Thesteam port 1670 is also positioned low in the steam-crude mixing zoneand away from the exit end (toward the left of drawing figure) toprovide space for the steam bubbles to fully condense before exiting thesteam-crude mixing zone or from contacting an outside wall of thesteam-crude mixing zone. As the steam is less dense than the crude oil,the bubbles are expected to progress with the flow of the crude andprogress upward.

In FIG. 19, another alternative embodiment of the steam injection portis shown at 1770. In this arrangement, the port is physically largerthan the port in FIG. 17, but includes a shower-head like nozzle with aplurality of orifices to emit steam while preventing crude oil frombacking up into the steam injector. This is expected to produce a largernumber of small bubbles to reduce the time and space needed for thesteam bubbles to fully condense and collapse.

Turning now to FIG. 20, a further alternative embodiment of the steaminjection port is shown at 1870. This embodiment is similar to the twoprevious embodiments in that it includes a great many small orifices toproduce smaller steam bubbles, but also positions the port low in thesteam-crude mixing zone 1860 and closer to the inlet end and away fromthe exit end. This embodiment has an appearance suggestive of an ironingboard. Again, the steam bubbles are intended to mix with and collapsefully within and surrounded by the crude oil and not against a side wallof the pipe or mixing zone 1860.

Turning to FIG. 21, an arrangement for admitting steam into crude oil isshown comprising a venturi type structure where a narrowed neck ispositioned between an expanding conical shaped steam-crude mixing zone1960 and the crude oil conduit 1915. In this arrangement, yet anotherembodiment for injecting steam into crude oil, the crude oil is causedto speed up due to the reduced cross section while steam is injectedfrom steam supply line 1955. The brief period of increased velocityincreases the turbulence of the crude oil which also increases themixing of steam bubbles with crude oil to enhance the opportunity forthe steam bubbles and resulting water droplets to contact and capturesalt into larger water droplets more amenable to gravity separation. Theviolence of the increased turbulence in this system is far, far lessthan the turbulence created at a high shear mixer of current desaltingtechnology, but does create conditions that increase the contactsbetween steam bubbles and suspended salt in the crude.

FIG. 22 also shows an interesting arrangement for injecting steam into aflow a crude oil. The crude oil enters a vortex steam-crude mixing zone2060 via crude oil conduit 2015 while the steam injector 2055 injectssteam at the top of the vortex steam-crude mixing zone 2060. The crudeoil and steam bubbles flow in a vortex that spins down to the bottom.Along the way, the lower density steam bubbles collapse to waterdroplets that are higher density than the continuous phase crude oil. Assuch, the bubbles stay closer to the center and away from the outsidewall until fully collapsed and then congregate along the outside wallwhere coalescing of the droplets may occur. The steam-crude mixing zone2060 includes a non-moving, generally cylindrical space where high speedflow creates centrifugal forces. The kinetic forces developed byrelatively fast moving crude oil increase contacts between salt andwater whether the water is vapor or liquid and, as the contour of thesteam-crude mixing zone 2060 includes a progressively smaller diameterat the bottom, the forces driving coalescing increases as the mixture ofcrude oil and water reach their highest velocities creating early stagedensity-based separation at the bottom.

In yet another embodiment for injecting steam into crude oil to removesalt and other contaminants, FIG. 23 shows a steam injection port 2170comprising a spring biased plug that is pushed by a spring into the openbell end of a truncated cone steam pipe such that steam exits around theperiphery of the plug. This arrangement provides a means for adjustingthe size of the opening into the crude oil that should provide a levelof control of the size of steam bubbles entering the crude oil. Ideally,the steam pressure could be independently adjusted so that the springforce and steam pressure could alter the rate at which steam enters thecrude oil while maintaining relatively constant size bubbles orconversely maintain a constant flow of steam while altering the size ofthe bubbles. It would seem that larger bubbles would yield larger waterdroplet size which is better for gravity separation. However, there maybe situations or circumstances where smaller bubbles or smaller dropletsare desirable and the ability to modulate those sizes would be helpful.

A different, but similar arrangement is shown in FIG. 24 where steam isreleased at the interface of two cymbal-shaped plates 2270, but whereone of the plates is fixed and sealed to the end of the steam deliverysystem 2255 in fluid communication with the steam production system (notshown) and where steam is released at the common peripheral edges of theflush plates. The other plate is spring biased against the first tocreate a tight but not impervious interface. The spring force ispreferably adjustable to alter the steam flow rate and bubble sizeentering the steam-crude mixing zone. A control valve (not shown) in thesteam delivery line 2255 may be used in conjunction with the control ofthe spring force biasing the second plate to the first to control therate at which steam is added to the steam and the size of the steambubbles. The steam bubbles in this arrangement would be spaced wellapart to heat crude oil across a larger diameter of the steam-crudemixing zone 2260.

In FIG. 25, a different perspective of the present invention is shownwhere not only is steam added to the crude oil, but process chemicalsmay be added to the crude oil to aid with the capture of the salt orsubsequent removal of the water. A demulsifier would be a logicalchemical to add to the crude oil to aid in getting the small waterdroplets to separate from the crude oil. So, while steam is added to thesteam-crude mixing zone 2360 via steam injection system 2355, emulsifieris added through chemical injector port 2363. Using demulsifiers inconjunction with steam addition will aid in separating the resultingwater droplets from the crude oil in the settling vessel 1020. Suchchemicals are believed to work with any of the steam injectionarrangements shown in the prior figures.

In FIG. 26, to augment the steam injection into crude oil for desaltingcrude oil, turbulence or stirring of the crude oil is believed to aid inadditional salt capture and removal. To accomplish additional stirring,gas is injected into the crude oil to create a churning mixture wherethe gas is generally easily separable from the crude oil. So, while thesteam bubbles are intended to condense and collapse in steam-crudemixing zone 2460, gas bubbles are expected to remain in the crude oilwhile exiting the steam-crude mixing zone. Gas is shown to be injectedat feedline 2464 and removed by gas separator 2467. Gas separators areknown devices where gas goes out the top and the crude oil would passinto gravity separator 2460. The gas may be a light hydrocarbon gas suchas methane, ethane, propane, natural gas and other light hydrocarbonsalong with inert gases like nitrogen, carbon dioxide. Preferably gasesthat are easy to separate and create no undesired side reaction witheither contaminants or the crude oil are preferred. The gas provideskinetic energy to the crude oil to increase the likelihood and velocityof collisions of steam bubbles, water droplets and brine microdroplets.

Turning to another aspect of the present invention, the steam-crudemixing zone has been previously described as a section of the crude oilconduit or pipe such as shown at 2515 in FIG. 27 and as an enlargedsection of pipe or a vessel of any shape in which the steam may beinjected and the steam bubble would be delivered to contact the crudeoil alone and deliver its heat first to the crude oil and not directlyto the wall of the pipe or vessel. In FIG. 27, additional attention isgiven to the steam-crude mixing zone 2560 where it is shown to directthe crude oil in a downward direction. In this arrangement, the verticaldimension is sized to provide more than sufficient time and space forall of the steam bubbles to collapse before entering the settling tank2520. It should also be understood that this down draft mixing zone 2560arrangement is also compatible with other aspects of the presentinvention whether it includes the various injection devices or thesystem configurations shown in FIGS. 3-16. Since the steam bubbles areless dense than the crude oil, the steam bubbles tend to resist flow outthrough line 2561 leading to the gravity separator 2520 until all havecondensed and collapsed to liquid water giving refinery operatorsconfidence that no steam bubbles will escape from the mixing zone 2560.

FIG. 28 shows a contrary allegory to the FIG. 27 embodiment where thesteam-crude mixing zone 2660 has an up flowing orientation. It is sizedand operated to assure that all of the steam bubbles will have collapsedand condensed prior to entering the settling vessel 2620. Again, thisembodiment is compatible with the gas injection, chemical injection,each of the injector devices and the various system arrangements shownin FIGS. 3-16. One point worth noting, that is also shown in FIG. 28, isthat a rather large steam inlet 2655 may be employed in the invention.In some circumstances, steam may be readily available in adequatequantities where there is also a substantial opportunity to increase thetemperature of the crude oil by quite a lot. As such, the volume ofsteam that may be added could be sufficiently significant such that aparticularly large steam inlet 2655 would be needed. For example, iffive weight percent of steam is added to crude oil, this translates toadding about 500 volume percent steam to the crude oil. If six weightpercent of steam were to be added to the crude oil, this translates to600 volume percent added to the crude oil. While earlier describedembodiments were shown with small and medium orifices such as amillimeter in diameter or similar effective opening area (multipleorifices), it is conceivable that a multiple inch inlet may beappropriate perhaps up to 10 inches in diameter or an inlet having anequivalent effective cross sectional area. And, a large effective inletsize may be applied to just about any arrangement of the presentinvention.

In another aspect of the present invention, shown in FIG. 29, once thesteam bubbles have collapsed, then the focus is to get the waterdroplets to begin separating from the crude oil. Coalescer mixer 2769provides gentle, low shear arrangement stirring of the crude and watermixture in a manner that gets the water droplets to move together andincrease the probability of coalescing. This is done prior to thegravity separator 2720. The coalescer mixer comprises a helical blade ora segmented helical blade. This aspect is shown with the downwardoriented steam-crude mixing zone 2760, but may be used in combinationwith other aspects of the present invention.

As noted above, multiple aspects of the described invention arepotentially used together. In FIG. 30, one such combination is shownwhere steam is injected at a venturi injection line 2855 while a lightgas is added at feedline 2864 into an upflowing steam-crude mixing zone2860. Both chemical demulsifier and a light agitation gas are added at2863 and 2864, respectively, while the gas is removed at separator 2867.The water droplets are coalesced at coalescer mixer 2869 and thensubjected to gravity separation in gravity separator 2820.

In another combination, as shown in FIG. 31, water and high shear mixingare added to the embodiment shown in FIG. 30. The water is injected atfeedline 2916 the mixture is subjected to aggressive high shear mixingat high shear mixer 2917 downstream of the steam-crude mixing zone 2960.A corollary to FIG. 31 is shown in FIG. 32 where the water and highshear mixing is accomplished upstream of the steam injection. In thisarrangement the water is injected at water feedline 3016, aggressivelymixed at high shear mixer 3017 and the steam is injected by steaminjection system 3055.

It bears repeating that although the primary goal of the presentinvention is to take advantage of steam for desalting, one advantage ofthe present invention is that it is able to utilize both steam additionand wash water as in some refineries, steam is fully available and atother refineries or at other times, steam is available in limitedquantities. So, when steam volumes may be reduced, the volume of washwater may be added to continue to remove salt and contaminants, even ifnot as effectively as a steam only system. Moreover, there may also betimes when the crude oil has obtained a highest permissible temperatureprior to entering the first stage of the refinery. Heat management in arefinery tends to be a rather inflexible balance. So, again, even ifthere is sufficient steam volume to remove salt and contaminants, thecrude is already at the upper limit of the temperature and adding washwater performs more of the important function of desalting, but addslittle heat to crude oil that is at its upper limits.

In closing, it should be noted that the discussion of any reference isnot an admission that it is prior art to the present invention,especially any reference that may have a publication date after thepriority date of this application. At the same time, each and everyclaim below is hereby incorporated into this detailed description orspecification as additional embodiments of the present invention.

Although the systems and processes described herein have been describedin detail, it should be understood that various changes, substitutions,and alterations can be made without departing from the spirit and scopeof the invention as defined by the following claims. Those skilled inthe art may be able to study the preferred embodiments and identifyother ways to practice the invention that are not exactly as describedherein. It is the intent of the inventors that variations andequivalents of the invention are within the scope of the claims whilethe description, abstract and drawings are not to be used to limit thescope of the invention. The invention is specifically intended to be asbroad as the claims below and their equivalents.

The invention claimed is:
 1. A process for removing salt from crude oilwherein the salt is in the form of particles of crystalline saltsuspended in the crude oil or as droplets of brine water suspended inthe crude oil, or both, wherein the process comprises the steps of: a)injecting steam into the crude oil in the form of steam bubbles that arelarger relative to any salt particles or relative to the any droplets ofbrine water so as to contact the steam bubbles with the crude oil alongwith any nearby suspended salt particles and brine droplets, such thateach single steam bubble is adapted to contact numerous salt particlesand brine droplets; b) condensing the steam bubbles into droplets ofliquid water while at the same time dissolving available salt particlesforming new brine droplets and also delivering liquid or vaporous waterfrom the steam bubbles into any available small brine droplets resultingin enlarged brine droplets having a size bigger than before the contactwith the steam to be more amenable for separation from the crude oil;and c) separating liquid water from the crude oil including water withsalt dissolved therein, wherein the process is more particularlycharacterized in that it does not include imposing high shear mixing ofuncondensed steam bubbles in the crude oil, and wherein the step ofinjecting the steam occurs in a steam-crude mixing zone having a top andbottom, where crude oil flows through the steam-crude mixing zone in adefined direction of flow and the steam is injected near the bottom ofthe mixing zone within the direction of flow.
 2. The process accordingto claim 1 wherein the step of injecting steam into a steam-crude mixingzone more particularly comprises injecting steam through a plurality oforifices near the bottom of the steam-crude mixing zone to allow thebubbles to move with the direction of flow but whereas the orifices arearranged so that the steam is not to reach any wall of the steam-crudemixing zone prior to the bubbles collapsing and condensing.
 3. Theprocess according to claim 1 wherein the step of injecting steam into asteam-crude mixing zone more particularly comprises injecting steam intoa segment of pipe through which crude oil is conveyed into the desaltingprocess.
 4. The process according to claim 1 wherein the step ofinjecting wherein the steam into a steam-crude mixing zone moreparticularly comprises injecting steam into a segment of pipe that has alarger diameter than the pipe through which crude oil is conveyed intothe desalting process by at least 15%.
 5. The process according to claim1 wherein at least 98% of the steam bubbles formed in the crude oilcondense and collapse in the crude oil without ever contacting any wallsof the steam-crude mixing zone prior to condensing and collapsing. 6.The process according to claim 1 wherein at least 99% of the steambubbles formed in the crude oil condense and collapse in the crude oilwithout ever contacting any walls of the steam-crude mixing zone priorto condensing and collapsing.
 7. The process according to claim 1wherein at least 99.5% of the steam bubbles formed in the crude oilcondense and collapse in the crude oil without ever contacting any wallsof the steam-crude mixing zone prior to condensing and collapsing. 8.The process according to claim 1 wherein at least 99.9% of the steambubbles formed in the crude oil condense and collapse in the crude oilwithout ever contacting any walls of the steam-crude mixing zone priorto condensing and collapsing.
 9. The process according to claim 1wherein the steam is injected through a steam injector having a crosssectional area of at least 100 mm² up to 2500 cm².
 10. The processaccording to claim 1 wherein the steam is injected in a manner todeliver water droplets having an average diameter of at least 10 micronsand up to about 150 microns after the steam bubbles have collapsed andcondensed.
 11. The process according to claim 1 further including thestep of adding demulsifier into the crude oil prior to the step ofseparating the liquid water from the crude oil.
 12. The processaccording to claim 1 wherein the steam is added to the crude oil atbetween 1 and 8 percent by weight steam to crude oil.
 13. The processaccording to claim 1 wherein the steam is added to the crude oil atbetween 2 and 6 percent by weight steam to crude oil.
 14. The processaccording to claim 1 wherein the steam is added to the crude oil atbetween 4 and 6 percent by weight steam to crude oil.